Astronomy quiz question: dark energy destiny

Astronomy 10 Quiz 12, Fall Semester 2007
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q12.3

[3.0 points.] Which one of the following choices best describes what dark energy may eventually do to the universe in the distant future?
(A) The expansion of space will continue forever, until matter fades away, or is torn apart.
(B) The expansion of space will eventually slow down and stop, and begin contracting as galaxies and stars collide in a "Big Crunch."
(C) Eventually produce enough antimatter to annihilate all matter in the universe.
(D) Stabilize the expansion caused by inflation, such that universe will remain the same size.
(E) Stabilize the contraction caused by dark matter, such that the universe will remain the same size.

Correct answer: (A)

Dark energy is responsible for the recent accelerating expansion of space in the universe. As dark energy is apparently created by space itself, the expansion of space creates more dark energy, which would in turn accelerate the expansion of space, etc. Thus the expansion would steadily increase such that universe would be subject to a "Big Rip" or "Big Tear," as distant galaxies and nearer galaxies recede faster than the speed of light, disappearing from our view, and then locally the expansion of space would rip apart matter itself, overcoming attractive gravitational, electromagnetic, and then nuclear forces.

The "Big Crunch" response (B) had previously been the prevailing prediction for the fate of the universe, before the discovery of accelerating expansion caused by dark energy. For a closed, matter-dominated universe, gravitational forces could eventually overcoming the expansion of space, resulting in slowing down, stopping, and possibly reversing the expansion of space.

Student responses
Section 1073
(A) : 16 students
(B) : 20 students
(C) : 2 students
(D) : 5 students
(E) : 2 students